Methods are already known by means of which textile fabrics are stiffened by applying a stiffening agent. According to the method known from Swiss Pat. No. 208 340 (to which British Pat. No. 510,203 corresponds), articles made from flexible fabrics are stiffened by applying a liquid, colourless stiffening agent to the semi-finished or finished articles. Following evaporation of a solvent in the liquid, this stiffening agent must exert no adhesive action on adjacent layers of fabric. The stiffening agent is applied in such a way that a graded stiffness or flexibility is obtained or, alternatively, said stiffness or flexibility varies according to the intended use. This varying degree of stiffness is obtained by covering individual areas of the articles when applying the stiffening agent, by using solutions with different concentrations, or by applying different quantities of stiffening agent, for example by means of spraying nozzles using a different pressure or by partly covering the fabric with wire netting with varying thickness during spraying.
In the method known from British Pat. No. 911 517, a plastic material which can set or be cured under the action of heat is applied to the article in the form of an aqueous dispersion, emulsion or melt. By means of an engraved roller or a hollow screen, the stiffening agent is applied in varying quantities, so that a different degree of stiffening is obtained in individual portions of the article.
The use of known printing processes, e.g. relief, intaglio or screen printing for applying the stiffening agent to the textile fabric is proposed by the method of German Disclosure Document (Offenlegungsschrift) DE-OS No. 25 35 593.
All the printing processes for applying the stiffening agent which are proposed in conjunction with the known methods have disadvantages. Quite apart from the fact that in the known printing processes the time required for applying the stiffening agent is relatively long, it is only possible to a limited extent to adapt the metering to the particular textile fabric to be treated. In addition, the known printing processes are not suitable for processing a stiffening agent which must be drop-forming, and not viscous, in order to flow in a satisfactory manner into the fibres. As a result, the known methods are time-consuming.